1. Field of the Invention
This invention relates generally to the field of packaging technology, and more specifically to tamper evident closures for containers.
2. Description of the Related Technology
Various beverages, foods, medicines and the like are delivered to the public in bottles or other containers that are provided with resealable closures. Such closures provide a benefit to the consumer in that the containers can be tightly sealed and resealed after opening, which prolongs the shelf life of the product and maintains freshness. Although resealable containers provide benefits to consumers, by their nature they permit unauthorized and sometimes undetectable tampering with the product. Accordingly, many modem consumer products are packaged using tamper evident closures, which are designed to make it apparent to a consumer that a container has been opened.
Many conventional tamper evident closures utilize what is commonly known as a tamper evident band, which is designed to be retained by the container and to rupture or become separated from the consumer removable portion of the closure during opening. Typically, the container itself will include an annular ring or other retention structure for engaging the tamper evident band. The tamper evident band and the mating retention structure of the container are usually designed so that the tamper evident band will slip over the retention structure without damage during the initial application of the closure onto the container at the packaging plant, but that subsequent removal of the tamper evident band from the container will be difficult.
One type of tamper evident band that is in commercial use includes a first portion that is frangibly connected to the consumer removable portion of the closure and a second retention portion, commonly known as a J-hook, that is molded so as to angle radially inwardly and upwardly from a lower portion of the tamper evident band in order to engage retention structure on the container. During initial application of the closure, the retention portion will slip over the retention structure because of the inward and upward angling, but once it slips over the retention structure it will lock against the lower side of the retention structure, making it difficult to remove the tamper evident band from the container. An example of such a closure is disclosed in U.S. Pat. No. 5,400,913 to Kelly. Such closures are valued for their strength and ease of application.
Unfortunately, because of the inherent elasticity of some types of plastic materials, particularly at elevated temperatures, it is possible in some instances for a closure to be removed from the container with the tamper evident band still joined to the closure. Although, it is to be emphasized, this is a relatively rare occurrence, it is to be taken seriously as it frustrates the fundamental purpose of a tamper evident closure.
Other types of closures have been developed that ensure separation of the tamper evident band from the closure during opening by arresting rotational movement of the tamper evident band with respect to the closure during opening. One example of this would be U.S. Pat. No. 5,040,692 to Julian, which discloses a tamper indicating closure in which ratchet teeth are molded into the tamper evident band. These teeth engage similar projections that are molded beneath the finish portion of a container to which the closure is applied. While closures of this type are no doubt effective, they require the molding of a relatively thick tamper evident band, which increases material costs. Accordingly, for some applications that are more sensitive to material costs it would be economically difficult to apply such technology. Moreover, it is not possible to apply structure of the type that is taught in Julian for use in a closure that utilizes a J-hook type retention structure for the tamper evident band.
A need exists for an improved J-hook type retention structure for a tamper evident band that reduces the likelihood of the closure being unscrewed from a container without separation of the tamper evident band from the rest of the closure.